ENH: add action to generate human pangenome index and filter against it

[misialq]

This PR adds an action allowing to:

1. filter reads against the provided reference (mirrors filter-reads action from q2-quality-control)
2. if no reference was provided, build one from the human pangenome sequence and Grch38 genome, filter reads against it and return both, the filtered reads and the built reference.

If anyone wants to test this before merging, you'll need to install the missing dependencies: gfatools, seqtk and q2-quality-control.

To test, execute the following:

qiime moshpit filter-reads-pangenome \
  --i-reads <some reads artifact> \
  --p-n-threads N \
  --o-filtered-reads filtered.qza \
  --o-reference-index new-index.qza

After the first go, you can then try to use the index obtained through that action to test whether things work when an index is provided:

qiime moshpit filter-reads-pangenome \
  --i-reads <some reads artifact> \
  --i-index new-index.qza \
  --p-n-threads N \
  --o-filtered-reads filtered.qza \
  --o-reference-index newer-index.qza

After the second run new-index.qza and newer-index.qza should be the same artifact.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.93%. Comparing base (0914dd1) to head (dfb9bd8).
Report is 1 commits behind head on main.

Additional details and impacted files

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- Coverage   98.42%   97.93%   -0.50%     
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  Files          81      150      +69     
  Lines        4448     9143    +4695     
  Branches        0      404     +404     
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+ Hits         4378     8954    +4576     
- Misses         70      140      +70     
- Partials        0       49      +49     

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[ChristosMatzoros]

While I am waiting for the execution to be completed, here are some comments for some minor changes.

[ChristosMatzoros]

Hi @misialq, everything looks good to me now. Ready to merge!